Understanding PPM accuracy on a Laser Tracker

[lee01]

Sorry about this guys but my head is in bits at the moment and can not get my head around the following:

I’ve been looking into some Laser Tracker measurement devices and have come across an accuracy reading of +/- 2.5ppm and +/- 10ppm? What does this mean and how do you calculate this in normal micron format?


Many thanks for your assistance!

Lee01

 

[Rick Goodson]

lee01,

As with your previous post, there doesn't seem to be much help here. I am copying this to the 17025 thread. Maybe the MSA experts can help.

Regards,

 

[Ravi Khare]

Perhaps there will also be a specification on the least count too?

If there is, the + and - ppm would mean the number of times out of million readings that there can be an error in the measurement on either side of the least count tolerance.( the device will read wrong beyond the least count). This, usually will be derived statistically, from the repeatability histogram of the readings.

You should however get a clarification from the equipment manufacturers, in case their interpretation is a diffrernt one.

 

[Ryan Wilde]

lee01,

PPM stands for Parts Per Million. Therefore, your basic laser accuracy would be:

±2.5 PPM = 2.5 µm per meter
±10 PPM = 10 µm per meter


Ryan